Conventionally, there have been techniques for detecting the condition of a battery (such as the degree of deterioration or the remaining amount of charge) based on a voltage-drop characteristic of the battery during discharge for example at engine startup (refer to for example Patent Document 1). This voltage-drop characteristic is closely related to a unique load for each vehicle during discharge of the battery. Thus, in the conventional techniques of this kind, various parameters for evaluation of the battery's condition are individually set for each model.
Patent Document 1: Japanese Patent Application Laid-open No. 2004-190604
However, because of the individual setting of various parameters for evaluation of the battery's condition for each model, the aforementioned conventional techniques increase labor and equipment costs for parameter setting and are difficult to respond to variations due to individual differences among the same model of vehicles.